signature ATOMS_STRUCTS =
sig
end

signature ATOMS' =
sig
  include ATOMS_STRUCTS
  
  structure Id : ID
  structure Intl : INTL
  structure Label : LABEL
end

signature ATOMS =
sig
  include ATOMS'
  
  structure Atoms : ATOMS'  
  sharing Id = Atoms.Id
  sharing Intl = Atoms.Intl
end